In an increasing number of technical applications, it has become important to be able to accurately give the position of a mobile component relatively to a fixed mark for example, occasionally at a high frequency. Such is the case for example in a vehicle steering column or in machine tools performing complex machining operations, or even, again in the automotive field, for flaps of air-conditioning systems. The possible applications are countless and explain the exponential development of positioning sensors, in particular linear or angular sensors.
In fact, one of the driving factors influencing the demand for sensors having improved resolution is the anticipated development of electronically controlled steering systems, in which systems, safety is critical. In such systems, sensors must perform with extremely high reliability, often requiring redundancy in many forms. In these systems, the effect of an error in reported position can be dangerous, and the sensor must be able to self-diagnose when an error has occurred.
Several technologies may be used for detecting and measuring relative positions, the sensors which stem from the latter being, in most cases, associated with complex electronic processing means using interpolation algorithms which allow the position to be calculated.
Devices for locating a position relatively to a fixed mark, are thus already known, based on optical technologies, which however require, under nearly all assumptions, complex electronic processing of very basic optical information.